1. Field of the Invention
The present invention relates to a disk cartridge for housing an optical disk.
2. Related Background Art
Optical disks are required to be maintained always in a clean state so that recording and/or reproduction can be performed reliably. In order to prevent the adhesion of fingerprints from the touch of a finger, the occurrence of a flaw or the adhesion of dust, an optical disk is loaded into a drive for performing information recording and/or reproduction while housed in a disk cartridge. Generally, such disk cartridges are of a shutter type that includes a shutter for opening/closing windows into which an optical head, a turntable and a magnetic head are inserted. In the case where a shutter type disk cartridge is used in a changer drive, it is required that the disk cartridge housed in a stacker be conveyed from the stacker to a drive unit by a conveying means. This requires space in which the disk cartridge is moved, which has been a hindrance to higher-speed operation and size reduction.
JP 7(1995)-226045 A and the specification of U.S. Pat. No. 5,936,935 describe known examples of a conventional disk cartridge adapted to the use in compact changer drives that achieve higher-speed operation. These examples are the inventions made by the inventors of the present invention. The present invention was made to improve these examples further in terms of size reduction and optimization.
FIGS. 19A to 19E and FIGS. 20A and 20B show a configuration of a conventional disk cartridge that is applicable to the use in compact changer drives that achieve higher-speed operation. FIGS. 19A to 19E are external views of a disk cartridge 900 in a state of housing an optical disk. FIGS. 19A, 19B and 19C are a plan view, a side view, and a back face view, respectively. FIGS. 19D and 19E are a side view of a rear portion and a side view of a front portion, respectively. Further, FIGS. 20A and 20B show a state where the optical disk is pulled out together with an inner case to such a degree that recording and/or reproduction can be performed. FIG. 20A is a sectional plan view, and FIG. 20B is a sectional side view. FIG. 20B also shows a spindle motor, an optical head, a magnetic head and the like that are used to perform recording and/or reproduction.
As shown in FIGS. 20A and 20B, the disk cartridge 900 includes an outer case that is composed of a lower case half 902 and an upper case half 903, an inner case 904 that is housed in a space within the outer case such that the inner case 904 is allowed to come in and out, and a locking member 905 for preventing the inner case 904 housed in the outer case from being pulled out unintentionally.
An optical disk 901 is placed in a circular concave portion 904a of the inner case 904. The concave portion 904a is set to have an inner diameter somewhat larger than an outer diameter of the optical disk 901 so that the optical disk 901 can be rotated in the concave portion 904a. Projections 904i projecting in a central direction are formed in an upper portion of a peripheral wall of the concave portion 904a. The projections 904i function to prevent the optical disk 901 from coming out of the concave portion 904a. 
A pair of the locking members 905 are disposed on both sides of a front end of the inner case 904 in a pull-out direction. When the inner case 904 is housed in the outer case, a convex portion 905a of each of the locking members 905 is fitted in a concave portion (not shown) that is formed on an inner side wall of the outer case, thereby allowing the inner case 904 to be controlled so as not to be pulled out from the outer case. When the disk cartridge 900 is loaded into a drive, a pair of pull-out pins 920 that are provided in the drive are inserted respectively into a pair of U-shaped notches 904k in directions indicated by arrows 920a and subsequently moved outwardly within the notches 904k. As a result, each of the locking members 905 is rotated about a supporting shaft 905b, so that the engagement between the convex portion 905a and the concave portion of the outer case is released (that is, a lock is released). Then, the pull-out pins 920 are moved in a direction indicated by an arrow 920b, and thus the inner case 904 is pulled out from the outer case.
After that, as shown in FIG. 20B, from one side of the optical disk, a turntable 911 of a spindle motor and an optical head 913 that are provided in the drive move respectively toward the optical disk 901, and from the other side of the optical disk, a damper 912 and a magnetic head 914 move respectively toward the optical disk 901, which brings about a state for recording and/or reproduction. Although the magnetic head 914 is necessary in the case where the optical disk 901 is a magneto-optical recording medium, it is not necessary in the case where the optical disk 901 is a phase-change type recording medium, and in the case where the drive is intended for reproduction only.
In order for the above-mentioned conventional disk cartridge 900 to be brought to a state of recording and/or reproduction, as shown in FIGS. 20A and 20B, it is required that the optical disk 901 be pulled out from the outer case by not less than half the size of the optical disk 901 so that space for constituent components of the drive such as the spindle motor, the optical head and the like can be secured. This requires a drive using this disk cartridge 900 to have an increased depth dimension L.
Furthermore, the above-mentioned conventional disk cartridge 900 is intended mainly for the use in changer drives. Generally, changer drives are of a stationary type, and thus in a changer drive, an increase in the depth dimension L is tolerated. However, for the use in mobile devices such as a notebook personal computer, a PDA (personal digital assistant), a camera, a movie camera and the like, a drive is required to be reduced in size, and thus an increase in the depth dimension L of the drive is not tolerated.
In providing optimization with respect to a changer drive, in the case where it is desired that a plurality of optical disks be handled always as a set, for example, a two-disk set, desirably, a plurality of disk cartridges for housing these disks are joined to each other so as not to be separated. The above-mentioned documents describe a configuration in which a plurality of disk cartridges are joined to each other using a joining member. A reduced size of a disk cartridge requires that a joining member also be reduced in size, and an excessive size reduction of the joining member leads to difficulty in performing a joining operation.
Furthermore, the disclosures of the above-mentioned documents do not include a method of positioning the inner case 904, a write-protect identifying member and the like. Generally, in a shutter type disk cartridge in common use, as shown in FIG. 21, in many cases, positioning is performed by a method in which a reference pin provided on a drive side is inserted into a reference hole 956 provided on a flat surface of a cartridge case for housing an optical disk. However, in this method, it is required that the disk cartridge or the reference pin on the drive side be moved relative to each other in a direction perpendicular to the flat surface of the cartridge case, i.e. in a thickness direction, and thus a drive is required to have an increased height, which has been disadvantageous. Further, as shown in FIG. 21, generally, a write-protect identifying member 957 is disposed on the flat surface of the cartridge case. It is required that a switch for detecting the write-protect identifying member 957 on the drive side be moved relative to the write-protect identifying member 957 in the direction perpendicular to the flat surface of the cartridge case, i.e. in the thickness direction, and thus the same problem of requiring the drive to have an increased height has been presented. Further, with the improvements in a recording density technique, a smaller disk diameter is achieved, and thereby furthering the size reduction of disk cartridges. A further size-reduction of a disk cartridge also results in an excessive size reduction of a write-protect identifying member, and thus the write-protect identifying member cannot be operated easily by fingers, which also is disadvantageous.